RP5 Endocrine Disruption and Pharmaceutical Issues
Thursday, 17 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(AGA-1117-854926) Contamination of Private Drinking Water Wells by Sulfonamide Antimicrobials from a Confined Animal Feeding Operation.

Aga, D.¹, Batt, A.¹, ¹ Chemistry Department, University at Buffalo, Buffalo, NY, USA

ABSTRACT- Samples from six private wells formerly used as source for drinking water by the residents of Washington County (Weiser, Idaho) were collected to assess the impact of a nearby confined animal feeding operation (CAFO) on the quality of the local groundwater. All six samples were found contaminated by two veterinary antibiotics, sulfamethazine (at concentrations between 0.076 to 0.22 to micrograms per liter) and sulfadimethoxine (at concentrations between 0.046 to 0.068 micrograms per liter). Analysis was performed using a validated solid phase extraction (SPE) and liquid chromatography with ion-trap mass spectrometry (LC/IT-MS/MS) method. Further, these groundwater samples contained elevated concentrations of nitrate and ammonia. Three of the sampled wells have nitrate levels that exceeded the maximum contaminant level set by the US Environmental Protection Agency for drinking water, with nitrate concentration as high as 39.1 mg/L. All but one well showed nitrate, which instead contained ammonia at 1.22 mg/L. Analysis of the nitrate and ammonia in these samples by isotopic ratio mass spectrometry indicated ¹⁵N characteristic of an animal or human waste source. Results from this study underscores the role of CAFO as an important source of antibiotic contamination of the groundwater. Prolonged exposure to low levels of antibiotics in the environment could result in a selective pressure which in turn favors the proliferation of antibiotic resistant bacteria. The detection of sulfonamides in groundwater previously used as source for domestic water supplies have important implications in the increasing emergence ofantibiotic resistance among pathogenic bacteria that affect human health.

Key words: antibiotics, groundwater, contamination, CAFO